R - Maarten van Steen

Failure detection
• Practice: the eventually perfect failure detector
• Has two important properties:
– Strong completeness: every crashed process is eventually suspected to have
crashed by every correct process.
– Eventual strong accuracy: eventually, no correct process is suspected by any
other correct process to have crashed.
• Implementation:
– If p did not receive heartbeat from q within time t → p suspects q.
– If q later sends a message (received by p):
– p stops suspecting q
– p increases timeout value t
– Note: if q does crash, p will keep suspecting q.
8.2 Process resilience: detection